DE102010062866B4 - Method for generating an operating strategy for an electric vehicle with range extender - Google Patents

Abstract

The invention relates to a method for generating an operating strategy for a vehicle (10) having an electric drive (20) with an electric motor (21) and a rechargeable vehicle battery (22), wherein a range extender unit (30) is provided with a service tank (32). and a power generation unit (31) for generating drive current for the electric motor (21) and for generating charging current for the vehicle battery (22) is provided; According to the invention, it is provided that - the specific energy costs (Knetz / Enetz) for the available energy quantity (Enetz) stored in the vehicle battery (22) are calculated on the basis of the electricity costs at the time of the last charging process and / or at the time of the next expected charging process, The specific energy costs (Knetz / Enetz) for the available energy quantity (Erex) stored in the fuel tank (32) are calculated on the basis of the fuel costs at the time of the last refueling operation and / or at the time of a next expected refueling operation, - the operating strategy is the activation range extender aggregate (30) when the quotient of the specific energy cost (Knetz / Enetz) of the amount of energy stored in the vehicle battery (22) and the specific energy cost (Knetz / Enetz) of the available fuel is greater than a predetermined factor ( s), and - the operating strategy is the Abscha The range extender aggregate (30) comprises, if the quotient of the specific energy cost (Knetz / Enetz) of the amount of energy stored in the vehicle battery (22) and the specific energy cost (Krex / Erex) of the available fuel is less than the predetermined factor (s is. Further, another solution is given with an operating strategy aimed at minimizing environmental damage.

Description

The invention relates to a method for generating an operating strategy for a vehicle with an electric drive with electric motor and a rechargeable vehicle battery, wherein a range extender unit is provided with a fuel tank for generating drive current for the electric motor or for generating charging current for the vehicle battery ,

State of the art

Electric vehicles have a significantly reduced range due to the limited energy density of electrical energy storage compared to a conventional motor vehicle with combustion drive. To extend the range so-called range extenders are used, which provide alternative to the traction battery electrical energy. In principle, different technologies are known for this purpose, such as, for example, fuel cells, gas turbines, reciprocating, Wankel or Sterling engines. In principle, traction battery and range extender can be selected between the two energy sources.

From the DE 10 2008 015 046 A1 a method for the predictive control of a hybrid drive of a motor vehicle is described, wherein this control takes place via a selection of an operating strategy. In this operating strategy at least one communication-based information is taken into account, which is generated by means of a communication of the motor vehicle with fixed and / or moving remote stations, for example by means of a vehicle-to-vehicle or vehicle-to-infrastructure communication. Information from digital maps whose information is based on a GPS signal can be used as a supplement. The aim of this known method is the optimized operation of the hybrid vehicle, in particular a large fuel economy.

Furthermore, the disclosure DE 198 31 487 C1 a method for operating a serial hybrid drive of a motor vehicle having an internal combustion engine, a battery and a generator as drive components, in which information relating to a route to be completed is acquired, which calculates expected power requirements for the hybrid drive over the course of the route under consideration of the acquired information be determined, and finally a control of the individual drive components over the course of the route regulating schedule, taking into account the respective efficiencies of the drive components or modes depending on the expected performance requirements. The information to be collected relates not only to the driving speed, the current driving and brake pedal position but also future traffic situations, such as driving distance, speed limits, Vorfahrtsstellen, traffic light phases, estimated average speed, recommended acceleration, traffic, slopes, gradients, etc. This information is partly wirelessly from regional , national or international databases, for example by means of GSM, transmitted to the motor vehicle.

Finally, out of the DE 10 2009 001 341 A1 a navigation method for a motor vehicle is known, in which are validly transmitted from a tank target whose energy prices to the motor vehicle and which are taken into account in the selection of the driver for route guidance offered route from the calculated routes. The route offered to the driver is determined in such a way that the energy costs calculated for the respective total routes, which are incurred while taking into account the respective energy prices and the additional consumption associated with the associated detours to the respective tank destination, are minimized.

From the US 2009/0050 383 A1 or even the US Pat. No. 7,013,205 B1 is an operating strategy for a hybrid vehicle with range extender aggregate known, which determines based on the electricity costs and fuel costs, the cheapest form of energy for the drive of the hybrid vehicle, and then the range extender aggregate on or off. Only the absolute energy costs (electricity costs, fuel costs) are compared and not the specific energy costs, which additionally take into account the available energy (available battery charge, available fuel) in the operating strategy of the range extender aggregate.

Disclosure of the invention

According to the invention, a method for generating an operating strategy for a vehicle with the features of patent claim 1 is proposed.

This inventive method realized on the basis of suitable data, a target size optimized deployment strategy of the range extender unit, wherein according to claim 1 as a target size, the specific energy costs for the operation of the electric drive the specific energy costs for the operation of the range extender to realize an optimized economic operation of the Vehicle are faced.

• – die spezifischen Energiekosten für die in der Fahrzeugbatterie gespeicherte verfügbare Energiemenge auf der Basis der Stromkosten zum Zeitpunkt des letzten Ladevorganges und/oder zum Zeitpunkt eines nächsten erwarteten Ladevorganges berechnet werden,
• – die spezifischen Energiekosten für die in dem Betriebsstofftank gespeicherte verfügbare Energiemenge auf der Basis der Betriebsstoffkosten zum Zeitpunkt des letzten Tankvorganges und/oder zum Zeitpunkt eines nächsten erwarteten Tankvorganges berechnet werden,
• – die Betriebsstrategie die Zuschaltung des Range-Extender-Aggregats umfasst, wenn der Quotient aus den spezifischen Energiekosten der in der Fahrzeugbatterie gespeicherten Energiemenge und den spezifischen Energiekosten des verfügbaren Betriebsstoffes größer als ein vorgegebener Faktor ist, und
• – die Betriebsstrategie die Abschaltung des Range-Extender-Aggregats umfasst, wenn der Quotient aus den spezifischen Energiekosten der in der Fahrzeugbatterie gespeicherten Energiemenge und den spezifischen Energiekosten des verfügbaren Betriebsstoffes kleiner als der vorgegebene Faktor ist.

This is inventively achieved in the method mentioned above, that

• The specific energy costs for the available amount of energy stored in the vehicle battery are calculated on the basis of the electricity costs at the time of the last charging process and / or at the time of the next expected charging process,
• The specific energy costs for the available amount of energy stored in the fuel tank are calculated on the basis of the fuel costs at the time of the last refueling and / or at the time of the next expected refueling,
• The operating strategy comprises the activation of the range extender aggregate when the quotient of the specific energy cost of the energy stored in the vehicle battery and the specific energy cost of the available fuel is greater than a predetermined factor, and
• - The operating strategy includes the shutdown of the range extender aggregate when the quotient of the specific energy cost of the amount of energy stored in the vehicle battery and the specific energy cost of the available fuel is less than the predetermined factor.

This solution is characterized by the fact that, from an economic point of view, an operating strategy of the range extender aggregate is made available which, for the respective operating state of the vehicle, indicates the economically most favorable form of energy for generating the driving force for the vehicle. The implementation of such an operating strategy can either be done automatically by means of a vehicle control unit or by means of a message in the form of a recommendation, which is displayed in a display unit for the driver.

Preferably, when the vehicle battery is charged from the public power grid, its electricity costs are used as a basis for calculating the specific energy costs and, in the case of an additional charge by means of the range extender aggregate, the specific energy costs arising from this charge.

In an advantageous embodiment of the invention, the factor is set to a constant value or as a function of the current and / or an expected battery charge state and / or as a function of the power request corresponding to the driver's request. This offers the possibility of temporarily valuating the assessment of the specific energy costs higher or lower.

It is advisable to determine the specific energy costs of the amount of energy stored in the vehicle battery from the costs for the amount of energy actually charged with the charging process, so that thereby the losses occurring up to the time of use of this energy are taken into account.

Since usually the fuel tank or the vehicle battery is not fully charged when refueling or when charging the vehicle battery from the public grid, training is provided that the specific energy costs when charging a not fully discharged vehicle battery and / or refueling a teilentleerten Fuel tanks are determined according to the proportions of residual charge and current load or residual fuel and currently fueled fuel. This achieves the most accurate possible determination of the specific energy costs.

Furthermore, according to one embodiment of the invention, it is advantageous to determine the amount of energy required to calculate the specific energy costs as a function of ambient conditions, preferably the ambient temperature and / or the route. Thus, environmental conditions can be taken into account, which generate different losses to generate the propulsion for the vehicle. Thus, for example, at low ambient temperatures, the use of energy from the vehicle battery is more lossy than the operation of a reciprocating engine of a range extender unit.

Since range extender units usually have several operating points to choose from, it is advantageous according to a further embodiment of the invention if the specific energy costs are determined on the basis of that operating point with a maximum amount of generated drive or charging energy.

According to the invention, the operating strategy can be advantageously extended such that the operating strategy, in addition to the specific energy costs, additionally damages the environmental damage caused in the generation of the energy charged in the last and / or the next expected charging process, in particular the emitted noxious gases, for example carbon dioxide and / or carbon dioxide Generation of drive and charging current caused by the fuel used in the last and / or next expected refueling operation caused environmental damage, in particular the emitted noxious gases, eg. Carbon dioxide are taken into account.

To optimize the operating strategy generated is in a further embodiment of the Invention provided that position-dependent, in particular environmental zones information, which are preferably provided by means of GPS and / or GSM and / or car-2-car communication and / or a digital map, are taken into account in the operating strategy. Thus, for example, in the context of a navigation route prior to entering an environmental zone with zero emission, a charging of the vehicle battery by means of the range extender unit can be performed predictably, if the state of charge of the vehicle battery is not sufficient for their complete passage or expand the operating strategy such that the range extender unit is not operated when passing through such a zero emission zone.

• – die bei der Erzeugung der in der Fahrzeugbatterie im letzten und/oder im nächsten erwarteten Ladevorgang der Fahrzeugbatterie geladenen bzw. zu ladenden Energie verursachten Umweltschädigung, insbesondere der emittierten Schadgase, vorzugsweise Kohlendioxyd berechnet wird,
• – die bei der Erzeugung von Antriebs- und Ladestrom aus dem im letzten und/oder im nächsten erwarteten Tankvorgang getankten bzw. zu tankenden Betriebsstoff verursachten Umweltschädigung, insbesondere der emittierten Schadgase, vorzugsweise Kohlendioxyd berechnet wird,
• – die Betriebsstrategie die Zuschaltung des Range-Extender-Aggregats umfasst, wenn dessen Umweltschädigung, insbesondere die emittierte Schadgasmenge, vorzugsweise die Kohlendioxydmenge geringer ist als die bei der Erzeugung der in die Fahrzeugbatterie geladene Energie verursachten Umweltschädigung, insbesondere die emittierte Schadgasmenge, vorzugsweise die Kohlendioxydmenge, und
• – die Betriebsstrategie die Abschaltung des Range-Extender-Aggregats umfasst, wenn dessen Umweltschädigung, insbesondere die emittierte Schadgasmenge, vorzugsweise die Kohlendioxydmenge größer ist als die bei der Erzeugung der in die Fahrzeugbatterie geladenen Energie verursachten Umweltschädigung, insbesondere die emittierte Schadgasmenge, vorzugsweise die Kohlendioxydmenge.

Another solution is characterized by the fact that

• The environmental damage, in particular the emitted noxious gases, preferably carbon dioxide, caused during the generation of the energy charged or to be charged in the vehicle battery in the last and / or the next expected charging process of the vehicle battery is calculated,
• The environmental damage, in particular the emitted noxious gases, preferably carbon dioxide, caused in the generation of drive and charging current from the fuel tanked or to be tanked in the last and / or the next expected refueling operation is calculated,
• The operating strategy includes the connection of the range extender aggregate, if its environmental damage, in particular the quantity of emitted harmful gas, preferably the amount of carbon dioxide is less than the environmental damage caused by the energy charged into the vehicle battery, in particular the quantity of emitted harmful gas, preferably the amount of carbon dioxide, and
• - The operating strategy includes the shutdown of the range extender aggregate, if the environmental damage, in particular the emitted amount of harmful gas, preferably the amount of carbon dioxide is greater than that caused in the generation of the charged in the vehicle battery energy damage, especially the amount of emitted harmful gas, preferably the amount of carbon dioxide.

Such an operating strategy for the range extender aggregate is mainly optimized for ecological operation of the vehicle. The implementation of such an operating strategy can be carried out automatically by means of a vehicle control unit and / or displayed by means of a message in the form of a recommendation, in a display unit for the driver.

Short description of the drawing

The invention will be described below with reference to an embodiment with reference to the 1 described in detail. These 1 shows a schematic representation of a vehicle with the essential components for explaining the invention.

Embodiment of the invention

To 1 includes a vehicle 10 , here an electric vehicle an electric drive 20 with an electric motor 21 that of a vehicle battery 22 is supplied as a traction battery with traction current.

The vehicle 10 further includes a range extender aggregate 30 with a power generation unit 31 and a fuel tank 32 for operating this power generation unit 31 , If this range extender aggregate 30 comprises an internal combustion engine, there is the power generation unit 31 from a combustion engine driving a generator, wherein the fuel tank 32 absorb the required fuel.

The power generation unit 31 can also be designed as a fuel cell unit whose hydrogen in a fuel tank 32 is stored.

The electric drive 20 as well as the range extender aggregate 30 is from at least one control unit 40 This is also regulated by the operating strategy generated according to the invention for operating the range extender aggregate 30 generates and controls accordingly. The information required for this receives the control unit 40 from an information gathering unit 60 , the information required to create the operational strategy 61 For example, be transmitted wirelessly by GPS, GSM or by means of a car-2-car communication.

To display information relating to the operating strategy, which is provided by the control unit 40 are generated is a display unit 50 intended.

The operating strategy includes the connection or disconnection of the range extender aggregate 30 Depending on the specific energy costs K _rex / E _rex compared to the specific energy costs K _net / E _net in an operation of the electric drive 31 with traction current from the vehicle battery 22 that was charged with this traction current from the public grid.

With K _rex or K _net , the energy costs of the range extender aggregate 30 or the energy costs of the public electricity grid with E _rex or with E _net, the amount of energy in the fuel tank 32 of the range extender aggregate 30 refueled fuel or the amount of energy charged from the public grid. K _net / E _net and K _rex / E _rex are quantities that represent specific energy costs.

These specific energy costs, K _net / E _net and K _rex / E _rex , are compared as follows. If K _net / E _net > s · K _rex / E _rex (or (K _net / E _net ) / (K _rex / E _rex )> s), becomes the range extender aggregate 30 switched on, in the other case, so if K _network / E _network <K · K E _rex / E _rex (or (K _network / E _network ) / (K _rex / E _rex <s), becomes the range extender aggregate 30 off.

• – Applikation auf einen konstanten Wert,
• – Bestimmung in Abhängigkeit des momentanen Batterieladezustands der Fahrzeugbatterie 22,
• – Bestimmung in Abhängigkeit des zukünftig erwarteten Batterieladezustands, oder
• – Bestimmung in Abhängigkeit der auf der Basis eines Fahrerwunsches ermittelten Leistungsanforderung.

The factor s for evaluating the energy cost of the range extender aggregate 30 can be used to temporarily rate energy costs higher or lower. There are several ways to determine the factor s.

• Application to a constant value,
• - Determination as a function of the current battery state of charge of the vehicle battery 22 .
• - determination depending on the expected future battery state of charge, or
• Determination as a function of the performance requirement determined on the basis of a driver's request.

The energy costs K _network from the public power grid in consideration of the charging time t _load of the vehicle 10 applicable electricity prices. Alternatively, however, it is also possible to take into account the currently valid electricity prices for the next expected charging process K _network (t _current ), as well as a correspondingly weighted combination K _network = (a · K _network (t _load ) + b · K _network (t _actual )) // (a + b), where a and b represent the weighting factors.

This can be useful if, for example, due to high price fluctuations very expensive electricity was charged, but this is not used, although the currently available electricity prices have long since fallen again.

The so determined energy price K _net should be the price in the vehicle battery 22 currently available _network (t _current ). For this purpose, the amount of energy paid is to be corrected by the losses incurred up to the present time. Typical losses to be considered for this arise, for example, when charging or fast charging the vehicle battery 22 , by self-discharge of the vehicle battery 22 during long service lives or due to high battery temperatures, which influence the charging efficiency.

This can also be the case of a potential charging the vehicle battery 22 current energy quantities to be reached ( _{net load} ) and a weighted combination of both values: E _network = (a · E _network (t _charging ) + b · E _network (t _current )) / (a + b), where a and b represent the weighting factors.

This weighting can prevent very high energy prices, such as those caused by self-discharge during a very long service life, from hindering the use of the traction battery.

The energy costs K _rex , ie the fuel costs, for example the fuel costs for the operation of an internal combustion engine, are optionally from the fuel price K _rex (t _refueling ) paid at the time of _fueling or from the currently valid fuel price K _rex (t _actual ) or a weighted combination according to K _rex = (a * K _rex (t _refuel ) + b * K _rex (t _current )) / (a + b) determined, where a and b represent the weighting factors. The data required for this 61 Be online at the required time of the information gathering unit 60 transmitted.

Again, it is possible that operation of the range extender aggregate 30 is prevented, if comparatively expensive fuel was fueled. This can be z. B. during a trip abroad or the case of range extender units that can be operated with different supplies. It makes sense here to consider the fuel costs K _rex (t _currently ), which must be assumed to be paid during the next refueling process.

When determining the range extender aggregate 30 amount of energy generated, it makes sense to take into account the resulting current losses. For example, the use of energy from the vehicle battery 22 at extremely hot or very cold environmental conditions energetically consuming than the operation of a designed as a reciprocating engine range extender unit 30 , This is the case, for example, when thawing the vehicle battery 22 much more energy is needed than through the increased friction of the cold lubricant in the reciprocating engine. In principle, for some range extender technologies it may also be conceivable to take into account the reducing vehicle weight during operation as a result of the burnt fuel.

If necessary for the operation of the range extender unit 30 a selection of different operating points is available, so the maximum of the achievable under the required framework energy can be used as the basis, so the operating point to be selected, which generates the maximum amount of energy.

The operating strategy for the operation of the vehicle 10 Instead of estimating the specific energy costs and minimizing them, it is possible to focus on minimizing the resulting environmental damage caused by the operation of the electric drive with the traction current stored in the public grid or by the operation of the range extender aggregate.

Environmental damage from the use of the public power grid is determined as follows:
Since a consideration of all the resulting environmental damage is a highly complex task, for the sake of simplicity, the simplification is made that the amount of generated noxious gas, here, for example, carbon dioxide CO _{2 is} determined. Again, a suitable balance between the emissions of N _network (t _current) during loading and the _network should emissions N (t _load), which would result in a future charging operation can be selected: N _network = (a · N _network (t _charge ) + b · N _network (t _current )) / (a + b), where a and b represent the weighting factors.

For this purpose, either fixed assumptions for the regionally applicable electricity mix or even dynamic information about the split _{currently in effect} at the location can be used. Are considered various environmental damage mechanisms, such. For example, the formation of nitrogen oxides, a corresponding weighting of the individual damage mechanisms of the networks C and S is useful: N _network = (c · C _network (t _load ) + d · S _network (t _actual )) / (c + d), where c and d represent the weighting factors.

The due to the range extender aggregate 30 The resulting damage to the environment must be suitably compared to the environmental damage of the power supply network, whereby simplifying the resulting environmental damage on the basis of the resulting CO ₂ emissions is determined, for example, the known for certification of a range extender engine known as reciprocating CO ₂ - and NO _x emissions are used.

Instead of solely considering fuel costs or environmental damage, a combined weighting of the fuel costs of the range extender aggregate may also be used 30 against environmental damage.

The control strategy according to the invention for the electric vehicle 10 with range extender aggregate 30 can be based on the vehicle 10 supplied position-dependent information to be extended.

Thus, knowing a zero-emission environmental zone on an expected or navigational route may provide predictive charging of the traction battery 22 by means of the range extender aggregate 30 take place, the vehicle battery 22 to a pre-selectable minimum state of charge (SOC-min). This minimum state of charge (SIC-min) can be determined by an estimate of the energy consumption for passing through a so-called environmental zone or set to a predetermined value.

The entry into such an environmental zone can, for example, in a navigation system of the vehicle 10 be determined by GPS or GSM transmitted position data.

The at a predictive charging for the vehicle battery 22 The amount of energy to be generated can be determined as a function of the value of a predictive range estimate. In order to achieve a higher range estimation, high-current consumers in the on-board network of the vehicle can 10 be successively reduced or switched off power.

Furthermore, as part of a route planning, an optimization of the mileage can be carried out with the specification of minimum energy costs.

In a required local zero emission, for example. In a game street, the operation of the range extender aggregate 30 get abandoned.

In an electric vehicle 10 the operating strategy is designed so that the battery energy reserve is maintained at such a level that the vehicle acceleration at all times from the vehicle battery 22 is reachable.

The in the control unit 40 each generated control strategy can by appropriate control and regulation of the electric drive 20 and the range extender aggregate 30 be performed automatically, at the same time the corresponding information on the display unit 50 be provided for the driver.

Alternatively, it is also possible in the control unit 40 generated control strategy only as a driving recommendation for the driver in the display unit 50 so that the driver makes the decision to implement this control strategy.

The notification of the operating strategy recommendation to the driver can visually, z. Ex. Via a display, acoustically, z. Eg a beep, or haptic, z. For example, via a force feedback function, done.

Claims (9)

Method for generating an operating strategy for a vehicle ( 10 ) with an electric drive ( 20 ) with electric motor ( 21 ) and a rechargeable vehicle battery ( 22 ), wherein a range extender aggregate ( 30 ) with a fuel tank ( 32 ) and a power generation unit ( 31 ) for generating drive current for the electric motor ( 21 ) or for generating charging current for the vehicle battery ( 22 ) is provided, characterized in that - the specific energy costs (K _Netz / E _network ) for the in the vehicle battery ( 22 ) stored energy amount (E _net ) are calculated on the basis of the electricity cost (K _net ) at the time of last charging and / or at the time of the next expected charging, - the specific energy costs (K _rex / E _rex ) for in the fuel tank ( 32 ) stored energy quantity (E _rex ) is calculated on the basis of the fuel costs (K _rex ) at the time of the last refueling operation and / or at the time of the next expected refueling operation, - the operating strategy the connection of the range extender aggregate ( 30 ), if the quotient of the specific energy costs ( _grid / _grid ) of the vehicle battery ( 22 ) and the specific energy cost (K _rex / E _rex ) of the available fuel is greater than a predetermined factor (s), and - the operating strategy, the shutdown of the range extender aggregate ( 30 ), if the quotient of the specific energy costs ( _grid / _grid ) of the vehicle battery ( 22 ) and the specific energy cost (K _rex / E _rex ) of the available fuel is less than the predetermined factor (s). Method according to Claim 1, characterized in that when the vehicle battery ( 22 ) Whose current charges (from the public power grid as a basis for calculating the specific energy costs K _net / _net E) and at an additional charge (by means of the range extender unit 30 ) additionally the specific energy costs (K _rex / E _rex ) arising from this charge are used. Method according to one of the preceding claims, characterized in that the factor (s) is set to a constant value or as a function of the current and / or an expected battery charge state and / or as a function of the driver request corresponding power requirement. Method according to one of the preceding claims, characterized in that the specific energy costs (K _Netz / E _net , K _rex / E _rex ) when charging a not fully discharged vehicle battery ( 22 ) and / or when refueling a partially emptied fuel tank ( 32 ) are determined according to the ratio of residual charge and current load or residual fuel and currently fueled fuel. Method according to one of the preceding claims, characterized in that the energy required for calculating the specific energy costs (K _net / E _net , K _rex / E _rex ) amount of energy (E _net , E _rex ) is determined as a function of environmental conditions. A method according to claim 5, characterized in that the environmental conditions of the ambient temperature and / or the driving distance correspond. Method according to one of the preceding claims, characterized in that the range extender aggregate ( 30 ) can be operated with multiple operating points and the specific energy costs (K _rex / E _rex ) are determined on the basis of that operating point with maximum amount of generated drive or charging energy. Method according to one of the preceding claims, characterized in that the operating strategy in addition to the specific energy costs (K _net / E _network , K _rex / E _rex ) additionally takes into account the damage caused in the generation of the last and / or expected in the next charging energy damage caused by the environment , Method according to one of the preceding claims, characterized in that position-dependent information which is provided by means of GPS and / or GSM and / or Car-2-Car communication and / or a digital map, be considered in the generation of the operating strategy.

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